1. Field of the Invention
The present invention relates to an image forming apparatus for specifying the type of the apparatus and a method of controlling the same.
2. Description of the Related Art
The recently increasing variety of office styles is producing demands for an image forming apparatus capable of coping with various office environments. Under these circumstances, not only an MFP (Multi Function Printer) having scanner and facsimile functions but also a single-function printer that mainly features a printing function is becoming rich in variety. However, developing individual models increases the development costs. It is therefore necessary to meet user needs while adapting common basic arrangements.
For example, printers include an apparatus having only a USB (Universal Serial Bus) I/F serving as an external interface to be connected to a host computer or the like, and an apparatus having a network I/F in addition to a USB I/F. There are also printers that do not support an optional paper feed cassette, a printer whose product line is broadened by changing the number of supported optional paper feed cassettes, and a printer capable of attaching a double-sided unit.
To simply design and produce the units of combinations assumed for the plurality of products as described above, selector terminals made of DIP switches or the like are necessary, and efficiency is reduced. To solve this problem, a method has been proposed which achieves commonality of units as much as possible and performs concentrated management while confirming the software ID or selector terminal state of one unit. For example, Japanese Patent Laid-Open No. 05-210470 proposes a printer which eliminates use of selector terminals and instead specifies a model based on a signal from a detector provided in a printer mechanism unit.
However, this prior art has the following problems. For example, in the method of specifying a model using a selector terminal or a method of specifying a model based on predetermined information stored in a nonvolatile memory, external stress such as noise may change the signal level of the selector terminal or the stored information.
In this case, if the product displays an error message and interrupts the operation, no problem is posed because the user can confirm the occurrence of error and work out a countermeasure. However, since the product purchased by the user sometimes performs operations different from its specifications without detecting any error, an option to be supported originally may not be able to operate, or an unexpected operation may accelerate degradation of components.
The technique described in Japanese Patent Laid-Open No. 05-210470 is an effective solution if a printing element such as a dot printer is driven, and the home position or relative position can accurately be detected mechanically. However, the technique is not applicable to an apparatus that drives no printing element. Additionally, a mechanism for independently generating pulses and a mechanism for detecting the number of pulses are necessary for specifying the model, resulting in an increase in cost.